﻿namespace Prism.Navigation.Regions;

/// <summary>
/// Defines a class that wraps an item and adds metadata for it.
/// </summary>
public class ItemMetadata : BindableObject
{
    /// <summary>
    /// The name of the wrapped item.
    /// </summary>
    public static readonly BindableProperty NameProperty =
        BindableProperty.Create(nameof(Name), typeof(string), typeof(ItemMetadata), null);

    /// <summary>
    /// Value indicating whether the wrapped item is considered active.
    /// </summary>
    public static readonly BindableProperty IsActiveProperty =
        BindableProperty.Create(nameof(IsActive), typeof(bool), typeof(ItemMetadata), propertyChanged: BindablePropertyChanged);

    /// <summary>
    /// Initializes a new instance of <see cref="ItemMetadata"/>.
    /// </summary>
    /// <param name="item">The item to wrap.</param>
    public ItemMetadata(VisualElement item)
    {
        // check for null
        Item = item;
    }

    /// <summary>
    /// Gets the wrapped item.
    /// </summary>
    /// <value>The wrapped item.</value>
    public VisualElement Item { get; private set; }

    /// <summary>
    /// Gets or sets a name for the wrapped item.
    /// </summary>
    /// <value>The name of the wrapped item.</value>
    public string Name
    {
        get => (string)GetValue(NameProperty);
        set => SetValue(NameProperty, value);
    }

    /// <summary>
    /// Gets or sets a value indicating whether the wrapped item is considered active.
    /// </summary>
    /// <value><see langword="true" /> if the item should be considered active; otherwise <see langword="false" />.</value>
    public bool IsActive
    {
        get => (bool)GetValue(IsActiveProperty);
        set => SetValue(IsActiveProperty, value);
    }

    /// <summary>
    /// Occurs when metadata on the item changes.
    /// </summary>
    public event EventHandler MetadataChanged;

    /// <summary>
    /// Explicitly invokes <see cref="MetadataChanged"/> to notify listeners.
    /// </summary>
    public void InvokeMetadataChanged()
    {
        MetadataChanged?.Invoke(this, EventArgs.Empty);
    }

    private static void BindablePropertyChanged(BindableObject bindableObject, object oldValue, object newValue)
    {
        if (bindableObject is ItemMetadata itemMetadata)
        {
            itemMetadata.InvokeMetadataChanged();
        }
    }
}
